1. Field of the Invention
The present invention relates to a joined body of two dissimilar types of aluminum alloy materials, and relates to a vehicle door.
2. Description of Related Art
Dissimilar aluminum alloy materials that are mutually dissimilar mainly in regard to component content, such as Mg, are known in the art. For instance, an Al—Mg aluminum alloy material (aluminum alloy material containing Mg/JIS (Japanese Industrial Standard) 5000-series aluminum alloy material) is greater in mechanical strength than an Al—Mg—Si aluminum alloy material (aluminum alloy material containing Mg and Si/JIS 6000-series aluminum alloy material). To join aluminum alloy materials, welding (e.g., spot welding, arc welding, laser welding, and friction-stir welding (friction-stir joining)), rivet joining (including SPR (self-piercing riveting)), bonding, etc., are known in the art; among which welding is frequently selected and performed.
Japanese Unexamined Patent Publication No. 2002-283069 discloses a friction-stir welding technique for joining an Al—Mg—Si aluminum alloy material and an Al—Mg aluminum alloy material by friction-stir welding. However, the above-mentioned Japanese Unexamined Patent Publication deals with the case where the two alloy materials to be joined by welding are an Al—Mg aluminum alloy material and an Al—Mg—Si aluminum alloy material which have a special (specific) shape, and does not disclose any technique of welding an Al—Mg aluminum alloy material and a plurality of Al—Mg—Si aluminum alloy materials.